Field of the Invention
The invention lies in the optoelectronics field. Specifically, the invention concerns an optoelectronic module for bidirectional optical data transmission, in which a transmitting component to emit radiation, a receiving component to receive radiation, a beam splitter with a beam splitter layer and a radiation focusing to focus the radiation are designed and arranged relative to each other, so that during operation of the optoelectronic module, at least part of a radiation emitted by the transmitting component is input coupled in an optical device, especially an optical waveguide, optically coupled to the optoelectronic module, and that at least part of the received radiation, output coupled from the optical device, is input coupled in the receiving component.
This type of module is known, for example, from European Patent Application EP 664 585. In this document a transmitting and receiving module for bidirectional optical message and signal transmission is described. In this known module a laser chip is arranged on a common support between two support parts, whose side surfaces, adjacent to the resonator surfaces of the laser chip, are provided with mirror layers and are sloped at an angle of 45xc2x0 to the resonator surfaces. Radiation emitted from the laser chip, parallel to the top of the common support, is diverted from one of these side surfaces by 90xc2x0 in the direction of a lens coupling optics attached to the support part and input coupled in an optical waveguide by means of this. Radiation output coupled from the optical waveguide, for which the mirror layers and the material of the support parts, as well as the common support, are at least partially transparent, is received by a photodiode arranged beneath the common support. The device, consisting of a laser chip, photodiode, common support and support parts, is incorporated in a hermetically sealed metal housing with a window.
Installation of the individual components of an optical electronic module designed in this way is very complicated. It requires a large number of process steps and adjustment of the individual components relative to each other is difficult. Moreover, large reflection losses occur because of the air gap between the lens and the mirror layer.
It is accordingly an object of the invention to provide an optoelectronic module, which overcomes the above-mentioned disadvantages of the heretofore-known devices and methods of this general type and which requires the least possible installation expense, permits the simplest possible adjustment of the individual components, and exhibits limited reflection losses.
With the foregoing and other objects in view there is provided, in accordance with the invention, an optoelectronic module for bidirectional optical data transmission, comprising:
a transmitting component emitting radiation;
a receiving component receiving the radiation;
a beam splitter with a beam splitter layer and a radiation focusing device to focus radiation;
said transmitting and receiving components, said beam splitter and said focusing device being and arranged relative to each other, so that during operation of the optoelectronic module, at least one part of the radiation emitted by the transmitting component is input coupled in an optical device optically coupled to the optoelectronic module, and that at least one part of the received radiation output coupled from the optical device is input coupled in the receiving component, characterized by the fact:
that a molded element is prescribed as beam splitter, which consists essentially of a material transparent to the emitted radiation and the received radiation, and in which the beam splitter layer is embedded,
that the molded element has at least a first side surface, a second side surface and a third side surface,
that the first side surface and the second side surface are sloped toward each other, that the third side surface and the second side surface or the third side surface and the first side surface are sloped toward each other.
that the first side surface and the third side surface or the second side surface and the third side surface are opposite side surfaces of the molded element,
that a transmitting component beam output surface of the transmitting component faces the first side surface,
that a receiving component beam input surface of the receiving component faces the second side surface,
that a beam input and beam output surface of the radiation focusing device faces the third side surface,
that the beam splitter layer is arranged so that it intersects both the beam axis of the emitted radiation and the beam axis of the received radiation, and
that the transmitting component beam output surface of the transmitting component is connected to the first side surface, the receiving component beam input surface of the receiving component is connected to the second side surface, and the beam input and beam output surface of the radiation focusing device is connected to the third side surface.
According to the invention, a molded element is provided as beam splitter in the optoelectronic module of the type mentioned at the outset, which consists essentially of a material transparent to the emitted radiation and the received radiation and in which the beam splitter layer is embedded. The configuration of the beam splitter according to the invention as a molded element has the particular advantage that its side surfaces can be used as reference and adjustment surfaces for all the components just mentioned of the optoelectronic module.
The molded element has at least a first side surface, a second side surface and a third side surface, in which the first side surface and the second side surface are sloped toward each other, especially perpendicular to each other. The third side surface is sloped to the second side surface or to the first side surface, in particular, has the included angle of 90xc2x0. The first and third side surfaces or the second and third side surfaces are the opposite side surfaces of the molded element and lie parallel to each other. A transmitting component radiation output surface of the transmitting component faces the first side surface of the beam splitter device, a receiving component radiation input surface of the receiving component faces the second side surface and a radiation input and radiation output surface of the radiation focusing device faces the third side surface. The beam splitter layer is arranged so that it intersects both the beam axis of the emitted radiation and the beam access of the received radiation.
Transmitting component beam output surface is to be understood to mean that side surface of the transmitting component through which the greatest part of radiation generated in the transmitting component emerges from it. Likewise, receiving component beam input surface means that side surface of the receiving component through which radiation being received by the receiving component is input coupled. The beam input and beam output surface of the radiation focusing device means that side surface of the radiation focusing device through which the radiation emitted by the transmitting component penetrates the radiation focusing device, and through which radiation received by the radiation focusing device from the optical device emerges from the radiation focusing device.
The transmitting component beam output surface is connected to the first side surface, the receiving component beam input surface is connected to the second side surface and the beam input and beam output surface of the radiation focusing device is connected to the third side surface. A radiation-transparent medium, like transparent synthetic resin that fills up any gap present between the individual surfaces, serves as means of connection. It is particularly advantageous if the transmitting component beam output surface has physical contact with the first side surface, i.e., if the spacing between the transmitting component beam output surface and the first side surface is smaller than or equal to one-tenth of the wavelength of the emitted radiation. Ideally, the transmitting component beam output surface lies on the first side surface. The same applies to the receiving component beam input surface and the beam input and beam output surface of the radiation focusing device. An optoelectronic module designed in this way according to the invention advantageously has very limited internal reflection losses.
A particular advantage of the optoelectronic module according to the invention is that is has a very limited space requirement.
In an advantageous modification of the optoelectronic module according to the invention the beam splitter is produced from at least two joined optical prisms and the beam splitter layer is arranged between the two optical prisms. Because of this, a simple and thus cost-effective manufacturing method for large numbers of pieces can be advantageously accomplished for the beam splitter.
In a particularly preferred variant of the optoelectronic module according to the invention, the beam splitter has the shape of a cuboid, the beam splitter layer lies in a diagonal plane of section of the cuboid and a plane of section lying perpendicular to the beam splitter layer has the shape of a rectangle, especially the shape of a square. Such so-called prism-cubes are advantageously particularly simple to produce in large numbers.
In another preferred modification of the optoelectronic module according to the invention the radiation focusing device has a support part, on which the beam splitter and transmitting component are attached. The support part consists essentially of a material, transparent to the emitted radiation and the received radiation, and the transmitting component and radiation focusing device are arranged on opposite sides of the support part. Because of this, the design size of the optoelectronic module, in particular, can be significantly reduced and the radiation losses in the optoelectronic module are further reduced. In a particularly preferred variant of this advantageous modification of the optoelectronic module, the support part is designed in one piece with the radiation focusing device.
Another preferred variant of the optoelectronic module according to the invention has a monitor diode, which has a monitor diode beam input surface facing a fourth side surface of the molded element. Here again, monitor diode beam input surface means that side surface of the monitor diode through which radiation being detected by the monitor diode penetrates it. The first side surface and the fourth side surface of the molded element are arranged so that, during operation of the optoelectronic module, at least part of the emitted radiation passing through the beam splitter encounters the monitor diode beam input surface. For example, they represent opposite side surfaces of the molded element and, in particular, lie parallel to each other. In this case, the second and third side surfaces are also opposite side surfaces of the molded element that are parallel to each other. Advantageously, the monitor diode is also attached to the support part and any gap present between the monitor diode beam input surface and the fourth side surface of the molded element is filled with a transparent material.
A particularly preferred modification of the optoelectronic module according to the invention, in which the molded element has the shape of a cuboid, the beam splitter layer lies in a diagonal plane of section of the cuboid, a plane of section of the cuboid lying perpendicular to the beam splitter layer has the shape of a rectangle, especially a square, and in which the second and third side surfaces are opposite side surfaces of the molded element, so that the radiation focusing device and the receiving component are arranged on opposite sides of the molded element, has the features that the beam axis of the emitted radiation and the beam axis of the received radiation enclose an angle of 90xc2x0, that the beam splitter layer is designed and arranged so that it reflects most of the emitted radiation, so that the beam axis of the reflected radiation runs parallel to the beam axis of the received radiation, and that it transmits at least part of the received radiation, so that this encounters the receiving component beam input surface.
Another particularly preferred modification of the optoelectronic module according to the invention, in which the molded element has the shape of a cuboid, the beam splitter layer lies in a diagonal plane of section of the cuboid, a plane of section of the cuboid lying perpendicular to the beam splitter layer has the shape of a rectangle, especially a square, and the first and third side surfaces are opposite side surfaces of the molded element, so that the beam focusing device and the transmitting component are arranged on opposite sides of the molded element, has the features that the beam axis of the emitted radiation and the beam axis of the received radiation run essentially parallel to each other, that the beam splitter layer is designed and arranged so that it transmits a part of the emitted radiation being input coupled in the optical device and mostly reflects the received radiation and diverts it to the receiving component.
It is also particularly advantageous if a blocking filter is arranged between the receiving component and the second side surface of the molded element, which is essentially nontransparent from the wavelength of the emitted radiation. On this account, crosstalk, i.e., direct transmission of signals for the transmitting component to the receiving component, can be prevented.
A preferred process for simultaneous production of at least two optoelectronic modules in efficient assembly, in which the radiation focusing device has a support part, on which the beam splitter and transmitting component are attached, in which the support part consists essentially of a material transparent for the emitted radiation and the received radiation, and in which the transmitting component and the radiation focusing device are arranged on opposite sides of the support part, has the following process steps:
a) Production of a wafer, consisting of a material transparent for the emitted radiation and the received radiation,
b) Formation or application of at least two radiation focusing devices on a main surface of the wafer, so that an intermediate space is present between two radiation focusing devices,
c) Application of a prism bar, in which a beam splitter layer lying along its longitudinal center axis on one of its diagonal planes is embedded, to the wafer so that the beam splitter layer comes to lie above the radiation focusing device;
d) Application of at least two transmitting components to the wafer, so that the transmitting component beam output surfaces of the transmitting components each face a first side surface of the prism bar and a single radiation focusing device is connected to each transmitting component,
e) Application of at least two receiving components on the prism bar, so that a single radiation focusing device is connected to each receiving component,
f) If prescribed, application of at least two monitor diodes on the wafer, so that one monitor diode is connected to each transmitting component, and
g) Serving of the wafer and, optionally, the prism bar in the intermediate space between two radiation focusing devices, so that separate functional units are formed, each of which has a support part, a beam splitter, a transmitting component, a receiving component and a radiation focusing device.
In the interest of completeness, it is mentioned here that simultaneous production of a number of equivalent components in the wafer composite is referred to in semiconductor technology as efficient installation.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in an optoelectronic module for bidirectional optical data transmission, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.